The amount of data communication in the present wireless communication is exponentially increasing due to prevalence of various mobile equipments such as smart phones. It is expected that the amount of data communication will increase hundred times more than now in a few years. Thus, the current LTE system could not accommodate the requirements of data usage amount. To address such problems, more and more base stations can be constructed additionally, but it may require enormous expenditures, and frequency resources are too restrictive. Thus, it is necessary to develop a next generation technology for wireless communication and access network that can efficiently accommodate enhanced network capacity and traffic variations in time and space and also can reduce network operating expenditure (OPEX) and capital expenditure (CAPEX).